Why should I avoid using the system Python?

The “system Python” refers to the Python interpreter that comes pre-installed with your operating system. On macOS and Linux systems, this is typically found at /usr/bin/python3. On Windows, it may be the Python installation available through the Microsoft Store or a manual system-wide installation.

Using the system Python directly for development work creates several risks and potential problems:

• Operating System Dependencies: Your operating system likely relies on the system Python interpreter to run essential system tools and utilities. If you modify the packages installed in the system Python environment (for example, by upgrading or removing packages), you might inadvertently break system functionality.
• Permission Issues: Installing packages into the system Python often requires administrator/root privileges. This is both a security risk and an inconvenience, as you’ll frequently need to use sudo or run as administrator to manage packages.
• Version Conflicts: Different projects may require different versions of Python or different versions of packages. When using the system Python, you’re locked into a single version that may not be suitable for all your work. Additionally, system-provided Python versions often lag behind the latest releases.
• Reproducibility Problems: When you share your code with others or deploy it to different environments, using system Python makes it harder to ensure consistent behavior. The system Python version and its pre-installed packages can vary significantly across different operating systems and versions.

Best Practices

Instead of using the system Python, you should:

• Use tools like uv or pyenv to manage multiple Python versions
• Create isolated virtual environments for each project
• Explicitly specify Python version requirements in your project configuration
• Document dependencies using pyproject.toml

This approach provides better isolation, reproducibility, and version control while protecting your system’s stability.